Structure and Dynamics of Ca in Clays, Mineral Phases of Concrete, and Ca-NOM Complexes: Natural Abundance Ca-43 NMR and Molecular Modeling Studies
EMSL Project ID
29391
Abstract
The objective of this research is to obtain preliminary Ca-43 NMR data for a variety of environmentally and technologically important materials including Ca-saturated clays, calcium silicate hydrate (CSH) minerals, and Ca-bearing natural organic matter (NOM) complexes. Ca is critical to the behavior of these and other inorganic materials as well to a wide range of biochemical and biomedical issues. Despite its importance, Ca structure and dynamics are seldom studied experimentally on the molecular-level. Solid-state NMR spectroscopy has significant potential in this regard, but the only NMR-active calcium isotope (Ca-43) has spin I = 7/2 and suffers from severe sensitivity limitations due to its small natural abundance (sensitivity relative to C-13 = 0.05). Recent research has, however, shown that Ca-43 line-widths are relatively narrow and that large sample volumes and moderately high magnetic fields (14.1 T) enable rather efficient natural abundance Ca-43 NMR studies of crystalline inorganic and organic Ca compounds. The sensitivity benefits of the high magnetic fields available at PNNL combined with sensitivity-enhancing pulse sequences should enable natural abundance Ca-43 NMR studies in more complex systems of environmental relevance, such as CSH minerals, Ca-clays, and Ca-NOM complexes. The experimental NMR efforts will be complemented and supported by molecular dynamics (MD) computer simulations of the same systems using the EMSL computational facilities. The results of these preliminary studies will be used in grant proposals and subsequent science-theme proposal(s) to EMSL. Due to the novelty of the methods/applications and importance of Ca in materials, environmental chemistry, and biology/biochemistry, the results should also lead to several high-impact rapid communications.
Project Details
Project type
Limited Scope
Start Date
2008-06-16
End Date
2008-08-16
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Bowers GM, and RJ Kirkpatrick. 2009. "Natural Abundance 43Ca NMR Spectroscopy of Tobermorite and Jennite: Model Compounds for C–S–H." Journal of the American Ceramic Society 92(2):545-548. doi:10.1111/j.1551-2916.2008.02906.x
Bowers GM, and RJ Kirkpatrick. 2011. "Natural Abundance 43Ca NMR as a Tool for Exploring Calcium Biomineralization: Renal Stone Formation and Growth." Crystal Growth & Design 11(12):5188-5191. doi:10.1021/cg201227f
Bowers GM, DL Bish, and RJ Kirkpatrick. 2008. "H2O and Cation Structure and Dynamics in Expandable Clays: 2H and 39K NMR Investigations of Hectorite." Journal of Physical Chemistry C 112(16):6430-6438. doi:10.1021/jp7119087